地表水中的浊度与总固体含量

Turbidity is an indirect measure of water clarity that determines how much light passes through water, while total solids is a direct measurement recording the total mass of solid particles suspended in water. Both quantify water clarity but use different methods: turbidity assesses light transmission, whereas total solids measures actual particle weight after evaporation.

Particle size and color both influence turbidity by affecting light scattering and absorption. Larger particles scatter longer wavelengths more than shorter wavelengths, while smaller particles scatter short wavelengths intensely. Darker particles absorb more light and lighter particles increase scattering, with darker particulates resulting in higher turbidity due to increased light energy absorption.

High levels of turbidity and total solids result from soil erosion, waste discharge, runoff, or changes in ecological communities including algal growth or abundance of benthic organisms that disrupt sediments into the water column. These factors increase suspended particle concentrations, reducing water clarity and quality.

High turbidity lowers water quality by absorbing heat, increasing water temperature and decreasing dissolved oxygen levels since warm water holds less oxygen. Reduced sunlight penetration decreases photosynthesis, and suspended solids can clog gills, smother eggs, reduce growth rates, and disrupt microhabitats of many aquatic organisms.

A Secchi disk is a metal disk with alternating black and white quarters (freshwater) or plain white (marine) attached to a marked rope. The disk is dropped into water until it can no longer be seen, and the rope length at disappearance is recorded as Secchi depth, which relates to water turbidity. However, this field method requires sunny conditions and shaded test areas.

Fill a turbidity column with 50 mL of sample water and a blank column with deionized water. Compare the visibility of black dots at the base of both tubes. If the sample is cloudier, add Standard Turbidity Reagent in 0.5 mL increments to the blank until turbidity matches. Record total reagent added and convert to Jackson Turbidity Units using a reference table.

Measure 100 mL of well-mixed sample water into a pre-weighed beaker using a graduated cylinder. Evaporate the water in an oven at 100°C for 48 hours to dry the residue. Cool the beaker, reweigh it, and subtract the initial beaker weight from the final weight to obtain residue mass. Convert this weight to mg/L using the appropriate calculation formula.